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451 lines
13 KiB
451 lines
13 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* eCryptfs: Linux filesystem encryption layer |
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* |
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* Copyright (C) 2004-2008 International Business Machines Corp. |
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* Author(s): Michael A. Halcrow <[email protected]> |
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* Tyler Hicks <[email protected]> |
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*/ |
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#include <linux/sched.h> |
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#include <linux/slab.h> |
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#include <linux/user_namespace.h> |
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#include <linux/nsproxy.h> |
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#include "ecryptfs_kernel.h" |
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static LIST_HEAD(ecryptfs_msg_ctx_free_list); |
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static LIST_HEAD(ecryptfs_msg_ctx_alloc_list); |
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static DEFINE_MUTEX(ecryptfs_msg_ctx_lists_mux); |
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static struct hlist_head *ecryptfs_daemon_hash; |
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DEFINE_MUTEX(ecryptfs_daemon_hash_mux); |
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static int ecryptfs_hash_bits; |
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#define ecryptfs_current_euid_hash(uid) \ |
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hash_long((unsigned long)from_kuid(&init_user_ns, current_euid()), ecryptfs_hash_bits) |
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static u32 ecryptfs_msg_counter; |
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static struct ecryptfs_msg_ctx *ecryptfs_msg_ctx_arr; |
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/** |
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* ecryptfs_acquire_free_msg_ctx |
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* @msg_ctx: The context that was acquired from the free list |
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* |
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* Acquires a context element from the free list and locks the mutex |
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* on the context. Sets the msg_ctx task to current. Returns zero on |
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* success; non-zero on error or upon failure to acquire a free |
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* context element. Must be called with ecryptfs_msg_ctx_lists_mux |
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* held. |
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*/ |
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static int ecryptfs_acquire_free_msg_ctx(struct ecryptfs_msg_ctx **msg_ctx) |
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{ |
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struct list_head *p; |
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int rc; |
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if (list_empty(&ecryptfs_msg_ctx_free_list)) { |
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printk(KERN_WARNING "%s: The eCryptfs free " |
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"context list is empty. It may be helpful to " |
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"specify the ecryptfs_message_buf_len " |
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"parameter to be greater than the current " |
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"value of [%d]\n", __func__, ecryptfs_message_buf_len); |
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rc = -ENOMEM; |
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goto out; |
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} |
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list_for_each(p, &ecryptfs_msg_ctx_free_list) { |
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*msg_ctx = list_entry(p, struct ecryptfs_msg_ctx, node); |
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if (mutex_trylock(&(*msg_ctx)->mux)) { |
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(*msg_ctx)->task = current; |
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rc = 0; |
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goto out; |
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} |
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} |
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rc = -ENOMEM; |
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out: |
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return rc; |
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} |
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/** |
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* ecryptfs_msg_ctx_free_to_alloc |
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* @msg_ctx: The context to move from the free list to the alloc list |
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* |
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* Must be called with ecryptfs_msg_ctx_lists_mux held. |
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*/ |
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static void ecryptfs_msg_ctx_free_to_alloc(struct ecryptfs_msg_ctx *msg_ctx) |
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{ |
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list_move(&msg_ctx->node, &ecryptfs_msg_ctx_alloc_list); |
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msg_ctx->state = ECRYPTFS_MSG_CTX_STATE_PENDING; |
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msg_ctx->counter = ++ecryptfs_msg_counter; |
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} |
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/** |
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* ecryptfs_msg_ctx_alloc_to_free |
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* @msg_ctx: The context to move from the alloc list to the free list |
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* |
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* Must be called with ecryptfs_msg_ctx_lists_mux held. |
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*/ |
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void ecryptfs_msg_ctx_alloc_to_free(struct ecryptfs_msg_ctx *msg_ctx) |
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{ |
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list_move(&(msg_ctx->node), &ecryptfs_msg_ctx_free_list); |
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kfree(msg_ctx->msg); |
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msg_ctx->msg = NULL; |
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msg_ctx->state = ECRYPTFS_MSG_CTX_STATE_FREE; |
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} |
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/** |
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* ecryptfs_find_daemon_by_euid |
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* @daemon: If return value is zero, points to the desired daemon pointer |
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* |
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* Must be called with ecryptfs_daemon_hash_mux held. |
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* |
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* Search the hash list for the current effective user id. |
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* |
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* Returns zero if the user id exists in the list; non-zero otherwise. |
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*/ |
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int ecryptfs_find_daemon_by_euid(struct ecryptfs_daemon **daemon) |
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{ |
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int rc; |
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hlist_for_each_entry(*daemon, |
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&ecryptfs_daemon_hash[ecryptfs_current_euid_hash()], |
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euid_chain) { |
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if (uid_eq((*daemon)->file->f_cred->euid, current_euid())) { |
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rc = 0; |
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goto out; |
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} |
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} |
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rc = -EINVAL; |
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out: |
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return rc; |
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} |
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/** |
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* ecryptfs_spawn_daemon - Create and initialize a new daemon struct |
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* @daemon: Pointer to set to newly allocated daemon struct |
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* @file: File used when opening /dev/ecryptfs |
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* |
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* Must be called ceremoniously while in possession of |
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* ecryptfs_sacred_daemon_hash_mux |
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* |
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* Returns zero on success; non-zero otherwise |
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*/ |
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int |
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ecryptfs_spawn_daemon(struct ecryptfs_daemon **daemon, struct file *file) |
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{ |
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int rc = 0; |
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(*daemon) = kzalloc(sizeof(**daemon), GFP_KERNEL); |
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if (!(*daemon)) { |
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rc = -ENOMEM; |
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goto out; |
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} |
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(*daemon)->file = file; |
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mutex_init(&(*daemon)->mux); |
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INIT_LIST_HEAD(&(*daemon)->msg_ctx_out_queue); |
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init_waitqueue_head(&(*daemon)->wait); |
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(*daemon)->num_queued_msg_ctx = 0; |
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hlist_add_head(&(*daemon)->euid_chain, |
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&ecryptfs_daemon_hash[ecryptfs_current_euid_hash()]); |
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out: |
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return rc; |
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} |
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/* |
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* ecryptfs_exorcise_daemon - Destroy the daemon struct |
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* |
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* Must be called ceremoniously while in possession of |
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* ecryptfs_daemon_hash_mux and the daemon's own mux. |
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*/ |
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int ecryptfs_exorcise_daemon(struct ecryptfs_daemon *daemon) |
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{ |
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struct ecryptfs_msg_ctx *msg_ctx, *msg_ctx_tmp; |
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int rc = 0; |
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mutex_lock(&daemon->mux); |
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if ((daemon->flags & ECRYPTFS_DAEMON_IN_READ) |
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|| (daemon->flags & ECRYPTFS_DAEMON_IN_POLL)) { |
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rc = -EBUSY; |
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mutex_unlock(&daemon->mux); |
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goto out; |
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} |
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list_for_each_entry_safe(msg_ctx, msg_ctx_tmp, |
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&daemon->msg_ctx_out_queue, daemon_out_list) { |
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list_del(&msg_ctx->daemon_out_list); |
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daemon->num_queued_msg_ctx--; |
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printk(KERN_WARNING "%s: Warning: dropping message that is in " |
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"the out queue of a dying daemon\n", __func__); |
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ecryptfs_msg_ctx_alloc_to_free(msg_ctx); |
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} |
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hlist_del(&daemon->euid_chain); |
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mutex_unlock(&daemon->mux); |
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kfree_sensitive(daemon); |
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out: |
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return rc; |
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} |
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/** |
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* ecryptfs_process_response |
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* @daemon: eCryptfs daemon object |
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* @msg: The ecryptfs message received; the caller should sanity check |
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* msg->data_len and free the memory |
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* @seq: The sequence number of the message; must match the sequence |
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* number for the existing message context waiting for this |
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* response |
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* |
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* Processes a response message after sending an operation request to |
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* userspace. Some other process is awaiting this response. Before |
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* sending out its first communications, the other process allocated a |
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* msg_ctx from the ecryptfs_msg_ctx_arr at a particular index. The |
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* response message contains this index so that we can copy over the |
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* response message into the msg_ctx that the process holds a |
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* reference to. The other process is going to wake up, check to see |
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* that msg_ctx->state == ECRYPTFS_MSG_CTX_STATE_DONE, and then |
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* proceed to read off and process the response message. Returns zero |
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* upon delivery to desired context element; non-zero upon delivery |
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* failure or error. |
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* |
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* Returns zero on success; non-zero otherwise |
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*/ |
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int ecryptfs_process_response(struct ecryptfs_daemon *daemon, |
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struct ecryptfs_message *msg, u32 seq) |
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{ |
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struct ecryptfs_msg_ctx *msg_ctx; |
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size_t msg_size; |
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int rc; |
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if (msg->index >= ecryptfs_message_buf_len) { |
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rc = -EINVAL; |
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printk(KERN_ERR "%s: Attempt to reference " |
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"context buffer at index [%d]; maximum " |
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"allowable is [%d]\n", __func__, msg->index, |
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(ecryptfs_message_buf_len - 1)); |
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goto out; |
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} |
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msg_ctx = &ecryptfs_msg_ctx_arr[msg->index]; |
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mutex_lock(&msg_ctx->mux); |
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if (msg_ctx->state != ECRYPTFS_MSG_CTX_STATE_PENDING) { |
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rc = -EINVAL; |
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printk(KERN_WARNING "%s: Desired context element is not " |
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"pending a response\n", __func__); |
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goto unlock; |
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} else if (msg_ctx->counter != seq) { |
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rc = -EINVAL; |
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printk(KERN_WARNING "%s: Invalid message sequence; " |
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"expected [%d]; received [%d]\n", __func__, |
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msg_ctx->counter, seq); |
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goto unlock; |
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} |
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msg_size = (sizeof(*msg) + msg->data_len); |
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msg_ctx->msg = kmemdup(msg, msg_size, GFP_KERNEL); |
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if (!msg_ctx->msg) { |
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rc = -ENOMEM; |
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goto unlock; |
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} |
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msg_ctx->state = ECRYPTFS_MSG_CTX_STATE_DONE; |
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wake_up_process(msg_ctx->task); |
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rc = 0; |
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unlock: |
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mutex_unlock(&msg_ctx->mux); |
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out: |
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return rc; |
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} |
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/** |
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* ecryptfs_send_message_locked |
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* @data: The data to send |
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* @data_len: The length of data |
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* @msg_type: Type of message |
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* @msg_ctx: The message context allocated for the send |
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* |
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* Must be called with ecryptfs_daemon_hash_mux held. |
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* |
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* Returns zero on success; non-zero otherwise |
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*/ |
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static int |
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ecryptfs_send_message_locked(char *data, int data_len, u8 msg_type, |
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struct ecryptfs_msg_ctx **msg_ctx) |
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{ |
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struct ecryptfs_daemon *daemon; |
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int rc; |
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rc = ecryptfs_find_daemon_by_euid(&daemon); |
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if (rc) { |
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rc = -ENOTCONN; |
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goto out; |
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} |
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mutex_lock(&ecryptfs_msg_ctx_lists_mux); |
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rc = ecryptfs_acquire_free_msg_ctx(msg_ctx); |
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if (rc) { |
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mutex_unlock(&ecryptfs_msg_ctx_lists_mux); |
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printk(KERN_WARNING "%s: Could not claim a free " |
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"context element\n", __func__); |
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goto out; |
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} |
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ecryptfs_msg_ctx_free_to_alloc(*msg_ctx); |
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mutex_unlock(&(*msg_ctx)->mux); |
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mutex_unlock(&ecryptfs_msg_ctx_lists_mux); |
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rc = ecryptfs_send_miscdev(data, data_len, *msg_ctx, msg_type, 0, |
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daemon); |
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if (rc) |
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printk(KERN_ERR "%s: Error attempting to send message to " |
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"userspace daemon; rc = [%d]\n", __func__, rc); |
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out: |
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return rc; |
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} |
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/** |
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* ecryptfs_send_message |
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* @data: The data to send |
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* @data_len: The length of data |
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* @msg_ctx: The message context allocated for the send |
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* |
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* Grabs ecryptfs_daemon_hash_mux. |
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* |
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* Returns zero on success; non-zero otherwise |
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*/ |
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int ecryptfs_send_message(char *data, int data_len, |
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struct ecryptfs_msg_ctx **msg_ctx) |
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{ |
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int rc; |
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mutex_lock(&ecryptfs_daemon_hash_mux); |
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rc = ecryptfs_send_message_locked(data, data_len, ECRYPTFS_MSG_REQUEST, |
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msg_ctx); |
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mutex_unlock(&ecryptfs_daemon_hash_mux); |
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return rc; |
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} |
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/** |
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* ecryptfs_wait_for_response |
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* @msg_ctx: The context that was assigned when sending a message |
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* @msg: The incoming message from userspace; not set if rc != 0 |
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* |
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* Sleeps until awaken by ecryptfs_receive_message or until the amount |
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* of time exceeds ecryptfs_message_wait_timeout. If zero is |
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* returned, msg will point to a valid message from userspace; a |
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* non-zero value is returned upon failure to receive a message or an |
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* error occurs. Callee must free @msg on success. |
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*/ |
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int ecryptfs_wait_for_response(struct ecryptfs_msg_ctx *msg_ctx, |
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struct ecryptfs_message **msg) |
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{ |
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signed long timeout = ecryptfs_message_wait_timeout * HZ; |
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int rc = 0; |
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sleep: |
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timeout = schedule_timeout_interruptible(timeout); |
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mutex_lock(&ecryptfs_msg_ctx_lists_mux); |
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mutex_lock(&msg_ctx->mux); |
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if (msg_ctx->state != ECRYPTFS_MSG_CTX_STATE_DONE) { |
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if (timeout) { |
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mutex_unlock(&msg_ctx->mux); |
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mutex_unlock(&ecryptfs_msg_ctx_lists_mux); |
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goto sleep; |
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} |
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rc = -ENOMSG; |
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} else { |
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*msg = msg_ctx->msg; |
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msg_ctx->msg = NULL; |
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} |
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ecryptfs_msg_ctx_alloc_to_free(msg_ctx); |
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mutex_unlock(&msg_ctx->mux); |
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mutex_unlock(&ecryptfs_msg_ctx_lists_mux); |
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return rc; |
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} |
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int __init ecryptfs_init_messaging(void) |
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{ |
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int i; |
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int rc = 0; |
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if (ecryptfs_number_of_users > ECRYPTFS_MAX_NUM_USERS) { |
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ecryptfs_number_of_users = ECRYPTFS_MAX_NUM_USERS; |
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printk(KERN_WARNING "%s: Specified number of users is " |
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"too large, defaulting to [%d] users\n", __func__, |
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ecryptfs_number_of_users); |
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} |
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mutex_lock(&ecryptfs_daemon_hash_mux); |
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ecryptfs_hash_bits = 1; |
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while (ecryptfs_number_of_users >> ecryptfs_hash_bits) |
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ecryptfs_hash_bits++; |
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ecryptfs_daemon_hash = kmalloc((sizeof(struct hlist_head) |
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* (1 << ecryptfs_hash_bits)), |
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GFP_KERNEL); |
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if (!ecryptfs_daemon_hash) { |
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rc = -ENOMEM; |
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mutex_unlock(&ecryptfs_daemon_hash_mux); |
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goto out; |
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} |
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for (i = 0; i < (1 << ecryptfs_hash_bits); i++) |
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INIT_HLIST_HEAD(&ecryptfs_daemon_hash[i]); |
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mutex_unlock(&ecryptfs_daemon_hash_mux); |
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ecryptfs_msg_ctx_arr = kmalloc((sizeof(struct ecryptfs_msg_ctx) |
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* ecryptfs_message_buf_len), |
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GFP_KERNEL); |
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if (!ecryptfs_msg_ctx_arr) { |
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kfree(ecryptfs_daemon_hash); |
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rc = -ENOMEM; |
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goto out; |
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} |
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mutex_lock(&ecryptfs_msg_ctx_lists_mux); |
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ecryptfs_msg_counter = 0; |
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for (i = 0; i < ecryptfs_message_buf_len; i++) { |
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INIT_LIST_HEAD(&ecryptfs_msg_ctx_arr[i].node); |
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INIT_LIST_HEAD(&ecryptfs_msg_ctx_arr[i].daemon_out_list); |
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mutex_init(&ecryptfs_msg_ctx_arr[i].mux); |
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mutex_lock(&ecryptfs_msg_ctx_arr[i].mux); |
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ecryptfs_msg_ctx_arr[i].index = i; |
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ecryptfs_msg_ctx_arr[i].state = ECRYPTFS_MSG_CTX_STATE_FREE; |
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ecryptfs_msg_ctx_arr[i].counter = 0; |
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ecryptfs_msg_ctx_arr[i].task = NULL; |
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ecryptfs_msg_ctx_arr[i].msg = NULL; |
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list_add_tail(&ecryptfs_msg_ctx_arr[i].node, |
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&ecryptfs_msg_ctx_free_list); |
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mutex_unlock(&ecryptfs_msg_ctx_arr[i].mux); |
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} |
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mutex_unlock(&ecryptfs_msg_ctx_lists_mux); |
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rc = ecryptfs_init_ecryptfs_miscdev(); |
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if (rc) |
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ecryptfs_release_messaging(); |
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out: |
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return rc; |
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} |
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void ecryptfs_release_messaging(void) |
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{ |
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if (ecryptfs_msg_ctx_arr) { |
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int i; |
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mutex_lock(&ecryptfs_msg_ctx_lists_mux); |
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for (i = 0; i < ecryptfs_message_buf_len; i++) { |
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mutex_lock(&ecryptfs_msg_ctx_arr[i].mux); |
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kfree(ecryptfs_msg_ctx_arr[i].msg); |
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mutex_unlock(&ecryptfs_msg_ctx_arr[i].mux); |
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} |
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kfree(ecryptfs_msg_ctx_arr); |
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mutex_unlock(&ecryptfs_msg_ctx_lists_mux); |
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} |
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if (ecryptfs_daemon_hash) { |
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struct ecryptfs_daemon *daemon; |
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struct hlist_node *n; |
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int i; |
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mutex_lock(&ecryptfs_daemon_hash_mux); |
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for (i = 0; i < (1 << ecryptfs_hash_bits); i++) { |
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int rc; |
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hlist_for_each_entry_safe(daemon, n, |
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&ecryptfs_daemon_hash[i], |
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euid_chain) { |
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rc = ecryptfs_exorcise_daemon(daemon); |
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if (rc) |
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printk(KERN_ERR "%s: Error whilst " |
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"attempting to destroy daemon; " |
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"rc = [%d]. Dazed and confused, " |
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"but trying to continue.\n", |
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__func__, rc); |
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} |
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} |
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kfree(ecryptfs_daemon_hash); |
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mutex_unlock(&ecryptfs_daemon_hash_mux); |
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} |
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ecryptfs_destroy_ecryptfs_miscdev(); |
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return; |
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}
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